Cushion sheet



Patented June 29, 1937 CUSHION SHEET William G. D.` Orr, Chicago, Ill., assignor to A. B. DickCompan'y, Chicago, Ill., a corporation of vIllinois Application September 1, 1936, Serial No. 98,866

2 Claims.

'I'his invention relates to4 cushion sheets for use in stencil-sheet assemblies, and aims to facilitate the cutting of stencils.

Two diiculties have lbeen encounteredin pre- 5 paring stencils by cutting an ordinary stencil sheet on a typewriter. One is da'ngercf cutting out the loop letters, and the` other is diiiculty in reading the words or marks which have been typed. To avoid these difficulties, stencil-sheet assemblies ha've been provided in which al cushion sheet is inserted between a stencil sheet and a backing sheet to cushion the blows of the y type and to makev the typing visible. The requirements for good cushioning and good visibil- 15 ity are, however, so antagonistic that, so far as I am` aware, there has been no stencil-sheet assembly which can provide both satisfactory cushioning and visibilty like that of ordinary typewriting, valthough each one of these del siderata has been attained separately without the L" other.

'By my invention, I have provided a new cushion sheet which yields suicientlyunder the blows of the typewriter to prevent the type from cutting the fibres of the base of the stencil sheet, and at the same time makes the portions of the stencil sheer, which have been struck by the type appear as `dark lines against a light background providing a visibility like that attained in ordinary twpewriting. I have obtained this result ing a porous andresilient cushion sheet carrying a small quantity f removable material of a color contrasting with the color of the stencil sheet and the color of the backing. 'Io obtain the fullest advantage of my invention, the stencil mass of the stencil sheet is made white by ,incorporating a white pigment in it; ,the backing sheet 'is of a white or light color; and the cushion sheet has a dark color such as dark blue. In this assemstruction consisting of a base sheet'of open, porous paper, such as yoshino paper, carrying a removable stencil mass or impregnating material r which weighs several times the weight of the paper and completely fills its interstices. A white or light-colored pigment is preferably incorporated inthe stencil mass. My new cushion sheet also includes a base sheet of'porous -and resilient n paper such as yoshino. It carries a removable colored material most. desirably consisting of a pigment and a vehicle therefor. The amount of colored material carried by the yoshino paper of the cushion sheet is manyV times less than the 55 amount of removable material with which the dark letters on alight background which may be by placing between a stencil sheet and its back,

bly, the stencil sheet may be of ordinary con- 'weight of the paper and completely lls the vsheet offyoshino paper Bl whose bres carry a yoshino paper of the stencil sheet is 4impregnated. The removable material of the cushion sheet vweighs less than the Weight of the yoshino paper to which it is'applied-preferably less than one-half the weight of the yoshino paper. It adheres to the fibres of the yoshino paper, but is insuicient to ll the interstices ybetween them, and consequently it does not alter the normally porous and resilient character of the'yoshino paper. 10

I have found that typing on such a stencilsheet assembly has the peculiar effect of causing an interchange of position vbetween the white or light-colored mass on the stencil sheet and the dark-colored material on the cushion sheet. 15.

part of the dark-colored material in the cushion lsheet is driven out upon the backing sheet, so that after typing the backing sheet also presents used in proof-reading. Perfect visiblity is thusY attained both on the stencil sheet itself and on the backing sheet. A

Since the dark-colored material of the cushion sheet, although sufficient to have the eiiects above described, does not iillthe interstices between the fibres of the yoshino paper or substantially alter the normal, porous and resilient character of this paper, the cushion sheet is ef- 35 fective to cushion the blows of the type and prevent'the type from cutting the fibres of the base of the stencil sheet.

A specific stencil-sheet assembly including 'a' cushion Sheet embodying my invention is shown in the accompanying drawing wherein parts are broken away and parts are magnified. In the drawing, A indicates a stencil sheet consisting of a base AI, of yoshino paper impregnated with a stencil mass A2 which weig'hs several times the intersticesbetween the fibres of the paper:. The

` stencil mass may consist of nitrocellulose and a tempering lagent, and is given a WhiteI color by a white pigment such as lithopone. Eleven per cent. of this material may be incorporated in the stencil mass, as in white stencil sheets heretofore i made.

B indicates a cushion sheet consisting of a the following composition:

small quantity of a removable darli-colored materiai B2. This material weighs slightly iess than one-half the weight of the yoshino paper and leaves the interstices of the paper operi.

C indicates an ordinary light-colored backing sheet which'may consist of manila paper. The cushion sheet B is prepared by impregnating a sheet of yoshino paper. with a liquid oi' Parts by weight Prussian blue I 4 .85 Castor oil 6,45 Oxalic acid .27 Alcohol, 88.43

and then allowing the alcohol to evaporate. It

will ybe noted that in thisy example the Prussian Y blue is a dark-colored pigment, the castor oil is a permanent oily vehicle for the pigment, the al'- cohol is a volatile solvent or dispersing` agent which serves to distribute the pigment and vehicle on the yoshino paper and then evaporates, and the oxalic acid is a peptizing agent which secures even distribution of the pigment.

` The use of a large proportion of volatile dispersing agent, which amounts in the example given to nearly ninety per cent. of the whole impregnating liquid, results in the deposit of a very small quantity of the' ynon--volatile ingredients on the yoshino sheet. The dark-colored material (Prussian blue and somel castor oil) remaining on the yoshino sheet after the evaporation of the alcohol amounts in weight to four-tenths the silient paper, and colored matter removably adhering to the ilbres of the paper and insuflicient in'quantity to ll the interstices between the fibres. l

2.v An open, porous and resilient cushion sheetfor use in a stencil-sheet assembly, com,- prising open, porous and resilient paper, and colored material removably'adhering tothe fibres of the paper and isufcient in quantity to substantially alter the normal open, porous and resilient character of the paper.

^ WILLIAM G. D. ORR.. 

